<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>交集选择器</title>
    <style type="text/css">
        p {color:silver;}
        .special {color:black;} /*交集选择器*/
        p.special {color:gray;}
    </style>
</head>
<body>
    <p>段落文本（银灰色）</p >
    <p class="special">段落文本（灰色）</p >
    <h3 class="special">标题文本（黑色）</h3>
</body>
</html>